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x86, bios: Make the x86 early memory reservation a kernel option 

Add a kernel command-line option so the x86 early memory reservation
size can be adjusted at runtime instead of only at compile time.

Suggested-by: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <tip-d0cd7425fab774a480cce17c2f649984312d0b55@git.kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
H. Peter Anvin 2010-08-25 16:38:20 -07:00
parent d0cd7425fa
commit 9ea77bdb39
3 changed files with 32 additions and 3 deletions
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5
Documentation/kernel-parameters.txt
View File

@ -2150,6 +2150,11 @@ and is between 256 and 4096 characters. It is defined in the file
Reserves a hole at the top of the kernel virtual
address space.
reservelow= [X86]
Format: nn[K]
Set the amount of memory to reserve for BIOS at
the bottom of the address space.
reset_devices [KNL] Force drivers to reset the underlying device
during initialization.

2
arch/x86/Kconfig
View File

@ -1326,7 +1326,7 @@ config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
Set whether the default state of memory_corruption_check is
on or off.
config X86_LOW_RESERVE
config X86_RESERVE_LOW
int "Amount of low memory, in kilobytes, to reserve for the BIOS"
default 64
range 4 640

28
arch/x86/kernel/setup.c
View File

@ -618,6 +618,8 @@ static __init void reserve_ibft_region(void)
reserve_early_overlap_ok(addr, addr + size, "ibft");
}
static unsigned reserve_low = CONFIG_X86_RESERVE_LOW << 10;
static void __init trim_bios_range(void)
{
/*
@ -627,9 +629,9 @@ static void __init trim_bios_range(void)
*
* This typically reserves additional memory (64KiB by default)
* since some BIOSes are known to corrupt low memory. See the
* Kconfig help text for X86_LOW_RESERVE.
* Kconfig help text for X86_RESERVE_LOW.
*/
e820_update_range(0, ALIGN(CONFIG_X86_LOW_RESERVE << 10, PAGE_SIZE),
e820_update_range(0, ALIGN(reserve_low, PAGE_SIZE),
E820_RAM, E820_RESERVED);
/*
@ -641,6 +643,28 @@ static void __init trim_bios_range(void)
sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
}
static int __init parse_reservelow(char *p)
{
unsigned long long size;
if (!p)
return -EINVAL;
size = memparse(p, &p);
if (size < 4096)
size = 4096;
if (size > 640*1024)
size = 640*1024;
reserve_low = size;
return 0;
}
early_param("reservelow", parse_reservelow);
/*
* Determine if we were loaded by an EFI loader. If so, then we have also been
* passed the efi memmap, systab, etc., so we should use these data structures